Process for treating steel for drawing



iron oxde, F6304, is left on the steel.

Patented Feb. 13, 19451 gorrica PROCESS FOR TREATING STEEL FOR DRAWING John-E. Millen, Cleveland, Ohio No Drawing.

Claims.

This invention relates to improvements in a process for treating steel preliminary to a drawing operation in a die. 7

An object of the present invention is to prepare steel for drawing without removing the scale which is formed thereon during ,the hot processes of manufacture which precede the cold drawing process.

Another object of the present invention is to prepare steel for drawing by the step by hydrating the metal oxide coating left on the steel by preceding hot processingsteps.

Other objects and advantages of the present invention will be apparent as the description proceeds and the essential features thereof will be summarized in the appended claims.

The conventional method of drawing steel wire begins with hot rolled rods which retain a coating of magnetic iron oxide. This coating of oxide or scale is removed by some suitable-method such as pickling in .acid or mechanical removal by shot blasting or bending the rod. The next step is to coat the clean rod with lime or similar material, after which it is baked in an oven and the rod or wire is then ready to be drawn througir a die using any of the suitable and customary lubricants just ahead of the entrance of the wire or rod into the die.

In my improved method the scale or magnetic introduce a new step which consists of changing the scale or iron oxide to the hydrated form by bringing the scaled surface into intimate contact with a heated solution of a water soluble alkali. Wire so treated may be drawn cold through a die in the usual manner with satisfactory results.

In a similar manner steel tubing which is conventionally cleaned of scale before drawing may be drawn with the scale on if the scale is first hydrated by the process step here disclosed.

Sheet steel to be pressed or drawn to form using male and female dies need not be cleaned, as is customarily done, but instead the scale "on the sheet steel may be hydrated by my improved in atank or vat where it may be heated. This to alkaline solution is preferably heated to approximately 160 F. or higher and the steel is immersed in the. heated solution for a period of several minutes, say of the order of five minutes.

Application November 5, 1943, Serial No. 509,118

on the steel for a sufiicient length of time, but I find immersion in a tank is simpler.

Another manner of carrying out my invention is to pass the heated steel into contact with the solution, which need not necessarily be preheated but which will become heated in contact with the hot steel. -.In this method of carrying out my invention the time of contact with the solution need only be of the order of a few seconds, say approximately fifteen seconds or longer. In thiscase the heated steel should be at a temper ature of approximately 600 F. or higher at the moment of contact with the alkalinesolution.

The alkalies or salts used in making up the above mentioned treating solution may consist or potassium, or also trisodium ,phosphatezor borax- These materials may be used combined in almost any proportion or any one of them may go be used-separately to make up the solution, This I then 80 group of materials includes NaOH K260:

' KOH KaSiO: I NazCOa NaaPOs NaaSiOs Na:B401

material is then given the conventional lightcoating of lime. In my new process it isvnot necessary to bake the lime coating in an oven as in prior processes although this will do no harm.

The lime coating is, however, allowed to dry and the rod or wire is then ready to be cold drawn by standard processes, that is, by pulling the filament through adie with suitable lubricants. Wire may be drawn by my improved process, as above described, through more than the usual number of standard die reductions without method which thus produces a coating which acts scratching and without any bad effect on the product ultimately produced.

If the wire is not drawn through too many proved process, it will retain a shiny black surface coating and will have considerably more resistance to oxidation and'corrosion than wire treated by the'usual known processes. In addition, the coating left on the wire by my hydratin; step aids inlubricating the wire during subsequent-drawing and fabrication.

Steel in other forms such as sheets or tubing Obviously. the heated solution might be sprayed on may be die drawn without first removing the of the hydrates, carbonates or silicates of sodium passes after being treated as above by my imscale, it the latter is hydrated in the manner set forth in the preceding paragraphs. It will be understood that my invention emb aces any process step wherein iron oxide scale on steel is brought into contact with a water soluble alkali under such conditions that the molecular activity is suflicient to hydrate the oxide. I believe the product thus formed on the surface of the steel is not a chemically hydrated oxide but is rather a mechanical or physical hydration analogo' s to water of crystallization.

Wha I claim is:

1. 'IJXG method of treating for drawing, steel havin a manufacturer's coating of magnetic iron oxide, consisting of the steps of hydrating the iron oxide, keeping the oxide coating intact gin the steel while drying, lime coating and dry- 2. The method of treating for drawing, steel having a manufacturers coating of magnetic iron oxide, consisting of the steps of hydrating the iron oxide, keeping the oxide coating intact on the steel while drying, lime coating and drying at room temperature.

3. The method of drawing steel having a coating of magnetic iron oxidecomprlsing the step of hydrating the iron oxide, keeping the coating intact on the steel, followed by a drawing operaion.

4. In the. cold drawing by means of a die, of steel coated with magnetic iron oxide, the-step of bringing the coated surface into intimate contact with a solution of a water soluble alkali in the presence of heat sufllcient to hydrate the oxide, keeping the coating intact on the steel, followed by a drawing operation.

to hydrate the oxide, keeping the coating intact on the steel, followed by a drawing operation.

, 6. In the cold drawing by means of a die, of steel coated with magnetic iron oxide, the step of bringingthe coated surface intointimate contact with a solution of one or more water soluble alkalies elected from the group; sodium hydroxide, sodium carbonate, sodium silicate, potassium hydroxide, potassium carbonate, potassium silicate, trisodium phosphate, borax, in the presence of heat sufficient to hydrate the oxide,

, keeping the coating intact on the steel, followed 5. In the cold drawing by means of a die, of

steel coated with magnetic iron oxide, the step of bringing the coated surface into intimate contact with a solution of a combination of water soluble alkalies in the presence of heat sufllcient by a drawing operation.

7. In the treatment for cold drawing by means of a die, of steel coated with iron magnetic oxide, the method step of immersing the coated surface in a solutionof a water soluble alkali heated to approximately 160 F. or higher, keeping the magnetic iron oxide coating intact on the steel, followed by a drawing operation.

8. In the treatment for cold drawing by means of a die, of steel coated with iron magnetic oxide,

' the method step of immersing the coated surface in a solution of a water soluble alkali heated to approximately 160F. or higher for a period of at least a few minutes, keeping the magnetic iron.

oxide coating intact on the steel, followed by a drawing operation.

9. In the treatment for cold'drawing by means of a die, of steel coated with iron oxide, the method steps of heating the steel to approximately 600 F. or higher and then bringing the coated surface into contact with" a water soluble alkali.

10. In the treatment for cold drawing by means of a die, of steel coated with iron oxide, the method steps of heating the steel to approximately 600 F. or higher and then bringing the coated 1 surface into contact with a water soluble alkali fill a period Of several seconds. 

